The present invention relates to a system and method for driving a low-speed component using a high-speed prime mover. More particularly, the present invention relates to a system and method for driving a low-speed component using a high-speed microturbine.
Microturbine engines are relatively small and efficient sources of power. Microturbines can be used to generate electricity and/or to power auxiliary equipment such as pumps or compressors. When used to generate electricity, microturbines can be used independent of the utility grid or synchronized to the utility grid. In general, microturbine engines are limited to applications requiring 2 megawatts (MW) of power or less. However, some applications larger than 2 MWs may utilize a microturbine engine.
Many microturbine engines include a turbine-compressor assembly that rotates at a high rate of speed. To generate electricity, the turbine-compressor assembly, or a separate turbine, is coupled to the generator, which also rotates at a high rate of speed. The generator output is then conditioned to produce a usable electrical current (e.g., 50 Hz or 60 Hz). In other constructions, a gearbox is positioned between the turbine and the generator to allow the generator to operate at a lower speed. However, due to the high speed of the turbine, the gearbox often requires several high-speed bearings to support the various gears. In addition, the dynamic and mechanical issues associated with the gearbox and turbine (e.g., vibration, imbalance, thrust loading, thermal expansion, and the like) can affect the operation of the other component. For example, a slight imbalance in the gearbox can produce a vibration that is transmitted to the turbine. The high speed of the turbine can act to increase the magnitude or the effect caused by the vibration. This can lead to undesirable operating conditions, system instability, and unwanted engine trips or shutdowns.